Balanced line type pulser circuit

ABSTRACT

A line type pulser circuit wherein a balanced supply source is used to charge a pair of pulse forming networks to equal potentials but opposite polarities via separate current charging circuits. The pulse forming networks are then discharged simultaneously into the primary winding of an output transformer. The secondary winding of the transformer is connected to a load requiring pulses of energy.

XX 03 1 Q2 83 23 3 [451 Nov. 13, 1973 4/1961 Oliver et 9/1966Badger...........

ABSTRACT A line type pulser circuit wherein a balanced supply source isused to charge a pair of pulse forming networks to equal potentials butopposite polarities via separate current charging circuits. The pulseforming networks are then discharged simultaneously into the 9 Claims, 1Drawing Figure PULSE FORMING NETWORK Primary Examiner-Alfred L. BrodyAttorney-Edward J. Norton et a1.

H03k 7/00 332/9 R, 12 B, 7, 332/5, 25; 331/6; 328/64, 65, 66, 230, 232;323/58 primary winding of an output transformer. The secondary windingof the transformer is connected to a [56] load requiring pulses ofenergy.

7 William Irving Smith, Burlington,

Assignee: RCA Corporation, New York, NY.

[22] Filed:

References Cited UNITED STATES PATENTS Bostick BALANCED LINE TYPE PULSERCIRCUIT Inventor:

Sept. 11, 1972 App]. No.: 287,722

United States Patent [191 Smith [58] Field ofSearch......................

27 GGER/ TRI NETWORK PATENIEI] NOV! 3 I975 PULSE FORM ING NETWORKBALANCED LINE TYPE PULSER CIRCUIT The present invention relatesgenerally to a line type pulser circuit and more particularly to a linetype pulser which employs a balanced technique.

There are certain types of pulse generator circuits which are designedfor particular types of loads which require pulse energy for theoperation thereof. Such loads may be, by way of example, a magnetrontube or a pulse operated laser. Generally, these pulse generators storeelectrical energy either in an electrostatic field or in a magneticfield. Provision is then made for the discharge of a fraction or all ofthis stored energy into the load.

There are two basic categories into which most pulser designs for theabove-mentioned type loads fall. They are: (a) those in which a smallfraction of the stored electrical energy is discharged into the loadduring a pusle; and (b) those in which all of the stored energy isdischarged during each pulse. These two categories are commonly referredto as (a) hard tube pulsers; and (b) line type pulsers. The presentinvention concerns itself with the type (b) or line type pulser.

Prior art line type pulsers generally take a form which includes a DCsupply, a single charging inductor, a single pulse forming network and aswitch connected across the supply and the charging inductor. A typicalprior art arrangement for a line type pulser may be found in US. Pat.No. 2,579,542.

One problem with the typical line type pulser is that the generation ofa pulse voltage level equal in magnitude to the source voltage levelusually requires the voltage with respect to ground at some point in thecircuit to exceed the magnitude of the source voltate. In airborneapplications it is especially desirable to keep voltage levels down dueto the potential arcing problems as a result of circuit operation atreduced atmospheric pressures.

The present invention provides a line type pulser wherein the pulselevel generated is substantially equal to the source voltage levelwithout requiring the voltage at any point in the circuit to exceed themagnitude of the supply voltage with respect to ground. An additionaladvantage provided by the present invention is that the holdoff voltagerequirement of the switching means is half that required for theconventional line type pulser.

In accordance with the present invention there is provided a line typepulser circuit having first, second and third terminals respectivelyadapted for connection to suitable source of a positive potential, anegative potential and a reference potential. There is also provided afirst and second voltage charging means connected between the first andsecond terminals with an intermediate point therebetween connected tothe point of reference potential. A first and a second current chargingmeans are respectively connected in circuit with the first and secondterminals. A first and a second pulse forming network are respectivelyconnected in circuit with the first and second current charging means.In addition, a transformer is provided with the ends of the primarywinding thereof connected to the first and secand pulse forming networkswith an intermediate point on the primary winding being connected to thepoint of reference potential. Means are provided for connecting autilization device to the secondary winding. Finally, a switching meansis connected to form a series path including the pulse forming networksand the primary winding of the transformer. The switching means isselectively operable for providing a low impedance in the path atpredetermined times.

The sole FIGURE in the drawing is a partial block and partial schematicdiagram of a preferred embodiment of a line type pulser utilizing thepresent invention.

Referring now to the sole Figure, there is provided a three phase ACsupply 10 having phases A, B and C and a neutral point 11 at a referencepotential, namely ground. In a typical airborne application, each of thephases A, B and C provided by supply 10 have a frequency of 1200 Hertzand differ in phase by from each other.

Diodes 12l 7 are provided in the form of a three phase full-wave bridgecircuit 18. Phase A is applied at a point between the anode of diode l2and the cathode of diode 13. Phase B is applied at a point between theanode of diode 14 and the cathode of diode 15. Phase C is applied at apoint between the anode of diode l6 and the cathode of diode 17.

One output terminal 19 of the bridge circuit 18 provides a positivevoltage lever whereas the output terminal 20 of the bridge circuit 18provides a negative voltage level. The voltage measured betweenterminals 19 and 20 is designated Vo. Thus far described the combinationof the three phase supply 10 and the full wave bridge circuit 18 may bethought of as a balanced DC supply circuit having a positive terminal19, a negative terminal 20 and a reference terminal 11, or groundedterminal.

Capacitors 21 and 22 are serially connected across terminals 19 and 20.An intermediate point between capacitors 21 and 22 is connected toground potential. Capacitor 21 charges up to a voltage of Vo/2 with theend nearest terminal 19 having a positive polarity charge. Capacitor 22charges up to a voltage level of Vo/2 with the end nearest terminal 20having a negative polarity charge.

One end of a current charging inductor 23 is connected to terminal 19and one end of a second current charging inductor 24 is connected toterminal 20. Inductors 23 and 24 provide surge current limiting for thecircuit.

The other end of induct'or 23 is connected to the anode of a gasdischarge thyratron tube 25. The cathode electrode of tube 25 isconnected to ground potential and to the anode electrode of a second gasdischarge thyratron tube 26. The cathode electrode of tube 26 isconnected to the other end of inductor 24. A trigger network 27 isprovided for simultaneously switching on tubes 25 and 26 by thesimultaneous application of gating signals to the respective gridelectrodes of tubes 25 and 26. Thyratron tubes are customarily used inthe present type of application, however, it is evident that otherswitching devices such as silicon controlled rectifiers may be used inplace of the tubes if desired.

A first pulse forming network 28 is connected on one end to the anode oftube 25 and a second pulse forming network 29 is connected on one end tothe cathode of tube 26. Pulse forming networks 28 and 29 serve as energystorage devices in the circuit and take the form of lumped-constanttransmission lines as is known in the art. Since networks 28 and 29serve not only as the source of electrical energy during the pulsegeneration time but also serve as pulse shapers, networks such as 28 and29 are commonly known as pulse forming networks or PENs.

The other end of network 28 is connected to one end of the primarywinding of transformer 30 while the other end of network 29 is connectedto the other end of the primary winding of transformer 30. The primarywinding of transformer 30 also has an intermediate point or tapconnected to ground potential. A load device 31, such as a magnetron orpulsed laser is connected in circuit with the secondary winding oftransformer 30. The turns ratio for transformer 30 is designed for theappropriate transformation of energy from the primary winding oftransformer 30 to the level of the impedance represented by load 31.

In operation, elements and 18 in combination with capacitors 21 and 22present equal magnitude and opposite polarity voltages of V0/2 to theinput terminals of charging inductors 23 and 24. Pulse forming network28 is charged to +Vo via charging inductor 23 and pulse forming network29 is charged to V0 via charging inductor 24. Thyratron switches 25 and26 are then triggered simultaneously from the trigger network 27. Thetriggering signals cause switches 25 and 26 to look like a low impedancepath to ground and thus networks 28 and 29 discharge their stored energyin series relationship through the transformer 30. The discharge ofenergy from networks 28 and 29 causes a pulse of voltage of magnitude V0to appear across the primary winding of transformer 30. Transformer 30then transforms the energy so discharged to the level required for theimpedance of the load 31.

From the foregoing, it is evident that pulse forming network 28 charges,via resonant charging inductor 23 and the ground return via one half ofthe primary winding of transformer 30, to a voltage level of V0. Sincethe anode electrode of tube 25 is connected between inductor 23 andnetwork 28 and the cathode thereof is connected to ground potential, themaximum voltage to be held off by tube 25 is Vo, i.e. the balanced linetype pulser output voltage level. Due to the symmetrical arrangement ofthe circuit, thyratron tube 26 will also hold off a maximum voltagelevel of V0.

In cases where a switching device is available which can hold off avoltage of 2V0, a single device, such as a tube may be used in place oftubes 25 and 26.

What is claimed is:

l. A line type pulser circuit comprising:

first, second and third terminals respectively adapted for connection toa source of a positive, a negative and a reference potential;

first and second voltage charging means connected in the order namedbetween said first and second terminals with an intermediate pointtherebetween connectable to said point of reference potential;

first and second current charging means respectively connected incircuit with said first and second terminals;

first and second pulse forming networks respectively connected incircuit with said first and second current charging means;

a transformer having a primary winding and a secondary winding, one endof said primary winding being connected to said first pulse formingnetwork, the other end of said primary winding being connected to saidsecond pulse forming network, said primary winding further having anintermediate point thereon connected to said point of referencepotential;

a switching means, having a normally high impedance, connected to form aseries path including said first and second pulse forming networks andsaid primary winding, said switching means being selectively operablefor providing a low impedance at predetermined times in said seriespath; and

means for connecting a utilization device in circuit with the secondarywinding of said transformer.

2. The circuit according to claim 1 wherein said first and secondvoltage charging means respectively include a first and a secondcapacitor.

3. The circuit according to claim 2 wherein said first and secondcurrent charging means respectively include a first and a secondinductor.

4. The circuit according to claim 3 wherein said switching meansincludes at least one gas discharge tube.

5. The circuit according to claim 3 wherein said switching meansincludes two gas discharge tubes serially connected to conduct currentin the same direction with a point between said two tubes connected tosaid point of reference potential.

6. A line-type pulser circuit comprising:

an energy supply source having first, second and third terminals, forproviding a positive potential, a negative potential and a point ofreference potential at said first, second and third terminalsrespectively;

a first capacitive energy storage means connected between said firstterminal and said point of reference potential;

a second capacitive energy storage means connected between said secondterminal and said point of reference potential;

a first inductive energy storage means having one end thereof connectedto said first terminal;

a second inductive energy storage means having one end thereof connectedto said second terminal;

a switching means having a normally high impedance connected between theother ends of said first and second inductive energy storage means, saidswitching means being selectively operable for providing a low impedancepath between said other ends of said first and second inductive energystorage means at predetermined times;

a first and a second pulse forming network;

a transformer having a primary and a secondary winding, said primarywinding having an intermediate tap connected to said point of referencepotential;

said first and second pulse forming networks and the primary winding ofsaid transformer being connected in circuit with said switching means;and

means for connecting a utilization device in circuit with the secondarywinding of said transfonner;

said utilization device being provided with a pulse of energy having apredetermined magnitude and a pulse width substantially dependent uponthe operation of said switching means.

7. The circuit according to claim 5 wherein said switching meansincludes at least one gas discharge tube.

8. The circuit according to claim 5 wherein said switching meansincludes two gas discharge tubes serially connected to conduct currentin the same direction three phase full wave bridge rectifier circuit forproviding said positive potential and said negative potential, with saidreference potential corresponding to the potential at said neutralterminal.

1. A line type pulser circuit comprising: first, second and thirdterminals respectively adapted for connection to a source of a positive,a negative and a reference potential; first and second voltage chargingmeans connected in the order named between said first and secondterminals with an intermediate point therebetween connectable to saidpoint of reference potential; first and second current charging meansrespectively connected in circuit with said first and second terminals;first and second pulse forming networks respectively connected incircuit with said first and second current charging means; a transformerhaving a primary winding and a secondary winding, one end of saidprimary winding being connected to said first pulse forming network, theother end of said primary winding being connected to said second pulseforming network, said primary winding further having an intermediatepoint thereon connected to said point of reference potential; aswitching means, having a normally high impedance, connected to form aseries path including said first and second pulse forming networks andsaid primary winding, said switching means being selectively operablefor providing a low impedance at predetermined times in said seriespath; and means for connecting a utilization device in circuit with thesecondary winding of said transformer.
 2. The circuit according to claim1 wherein said first and second voltage charging means respectivelyinclude a first and a second capacitor.
 3. The circuit according toclaim 2 wherein said first and second current charging meansrespectively include a first and a second inductor.
 4. The circuitaccording to claim 3 wherein said switching means includes at least onegas discharge tube.
 5. The circuit according to claim 3 wherein saidswitching means includes two gas discharge tubes serially connected toconduct current in the same direction with a point between said twotubes connected to said point of reference potential.
 6. A line-typepulser circuit comprising: an energy supply source having first, secondand third terminals, for providing a positive potential, a negativepotential and a point of reference potential at said first, second andthird terminals respectively; a first capacitive energy storage meansconnected between said first terminal and said point of referencepotential; a second capacitive energy storage means connected betweensaid second terminal and said point of reference potential; a firstinductive energy storage means having one end thereof connected to saidfirst terminal; a second inductive energy storage means having one endthereof connected to said second terminal; a switching means having anormally high impedance connected between the other ends of said firstand second inductive energy storage means, said switching means beingselectively operable for providing a low impedance path between saidother ends of said first and second inductive energy storage means atpredetermined times; a first and a second pulse forming network; atransformer having a primary and a secondary winding, said primarywinding having an intermediate tap connected to said point of referencepotential; said first and second pulse forming networks and the primarywinding of said transformer being connected in circuit with saidswitching means; and means for connecting a utilization device incircuit with the secondary winding of said transformer; said utilizationdevice being provided with a pulse of energy having a predeterminedmagnitude and a pulse width substantially dependent upon the operationof said switching means.
 7. The circuit according to claim 5 whereinsaid switching means includes at least one gas discharge tube.
 8. Thecircuit according to claim 5 wherein said switching means includes twogas discharge tubes serially connected to conduct current in the samedirection with a point between said two tubes connected to said point ofreference potential.
 9. The circuit according to claim 5 wherein saidenergy supply source includes a three phase source of alternatingcurrent including a neutral terminal and a three phase full wave bridgerectifier circuit for providing said positive potential and saidnegative potential, with said reference potential corresponding to thepotential at said neutral terminal.